Hand-held computers are relatively small personal computers that can fit in the palm of a user's hand. Conventional hand-held computers may include a display that is pivotally connected to a housing containing a processor and a keyboard. The display may be folded toward the keyboard in a stowed configuration when the computer is not in use, and the display may be pivoted away from the keyboard to allow access to both the keyboard and the display when the computer in use. The keyboard may include alphanumeric input keys and function keys that may be depressed in a conventional manner to send signals to the processor and to move images on the display.
One drawback with conventional keyboards for hand-held computers is that the input keys may be quite small and closely spaced, making the keyboard difficult to use. One conventional approach for addressing this problem has been to add folding flaps to the keyboard to provide more space for the input keys. For example, U.S. Pat. No. 5,187,644 to Crisan and U.S. Pat. No. 5,519,569 to Sellers each disclose a laptop-size computer keyboard having a central portion with two movable flaps. Each flap is pivotally connected to one edge of the central portion. Users fold the flaps over the central portion when the keyboard is not in use, and unfold the flaps away from the central position to access input keys on both the central portion and the exposed surfaces of the flaps. U.S. Pat. No. 5,519,569 further discloses scissored linkage arm assemblies that extend the input keys for operation and retract the input keys for storage.
One problem with the folding keyboards disclosed in U.S. Pat. Nos. 5,187,644 and 5,519,569 is that the flaps must be unfolded to access the input keys. Accordingly, the keyboards may not be easy to use in cramped environments where it is difficult or impossible to unfold the flaps. Another problem is that the input keys on the flaps may only be accessed when the flaps are in one position, i.e., the unfolded position. Accordingly, the keyboards may not be suitable or comfortable for users who may prefer to access the input keys when the flaps are in other, more comfortable positions. In fact, because the flaps must be unfolded to operate these computers, it may not be possible to use these computers in highly cramped environments in which the flaps cannot be adequately opened.
One approach to addressing some of the problems with folding keyboards has been to position input keys on both a top surface and a bottom surface of one of the flaps so that one set of input keys is accessible when the flap is folded and another set of input keys is accessible when the flap is unfolded. For example, U.S. Pat. No. 3,940,758 to Margolin discloses a calculator having three keyboard portions, including an upper portion, an intermediate portion, and a lower portion. Each of the keyboard portions is folded upon the other in a folded configuration and unfolded from the others in an unfolded configuration. Input keys on the top surface of the upper portion are accessible in the folded configuration, and input keys on the bottom surface of the upper portion are accessible in the unfolded configuration. A drawback with this approach is that it allows the user to access the input keys of the upper portion when the upper portion is in only two configurations, i.e., the folded configuration or the unfolded configuration, but does not allow the user to adjust the keyboard in either configuration. As discussed above, users may prefer to access the input keys when the upper portion is in any one of a variety of positions. Another problem is that each of the three portions, including the upper portion, is relatively small and may have space for only a limited number of input keys. Accordingly, when the keyboard is in the folded configuration, only a limited number of input keys are accessible.